\(a,\Leftrightarrow x\left(x+9\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-9\end{matrix}\right.\\ b,\Leftrightarrow\left(x+4-4\right)\left(x+4+4\right)=0\\ \Leftrightarrow x\left(x+8\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-8\end{matrix}\right.\\ c,\Leftrightarrow x\left(x-4\right)\left(x+4\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\\x=-4\end{matrix}\right.\\ d,\Leftrightarrow\left(x-5\right)^2=0\Leftrightarrow x=5\)

a) \(\Leftrightarrow x\left(x+9\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=-9\end{matrix}\right.\)

b) \(\Leftrightarrow x\left(x+8\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=-8\end{matrix}\right.\)

c) \(\Leftrightarrow x\left(x-4\right)\left(x+4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\\x=-4\end{matrix}\right.\)

d) \(\Leftrightarrow\left(x-5\right)^2=0\\ \Leftrightarrow x=5\)

\(a,\Leftrightarrow\left(x^2+2\cdot\dfrac{3}{2}x+\dfrac{9}{4}\right)+\dfrac{3}{4}=0\\ \Leftrightarrow\left(x+\dfrac{3}{2}\right)^2+\dfrac{3}{4}=0\\ \Leftrightarrow\left(x+\dfrac{3}{2}\right)^2=-\dfrac{3}{4}\left(vô.lí\right)\\ \Leftrightarrow x\in\varnothing\\ b,\Leftrightarrow\left(2x-5\right)\left(2x+5\right)=0\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-\dfrac{5}{2}\end{matrix}\right.\)

a)4x²+4x+1-x²-10x-25=0

`<=>(2x+1)^2-(x+5)^2=0`

`<=>(2x+1-x-5)(2x+1+x+5)=0`

`<=>(x-4)(3x+6)=0`

`<=>(x-4)(x+2)=0`

`<=>` \(\left[ \begin{array}{l}x=2\\x=-2\end{array} \right.\) 
b)(x^2+x+7)(x^2+x-7)=(x²+x)²-7x

`<=>(x^2+x)^2-7^2=(x^2+x)^2-7x`

`<=>-7^2=-7x`

`<=>-49=-7x`

`<=>x=7`

Vậy x=7

a) Ta có: \(\left(2x+1\right)^2-\left(3x-4\right)^2=0\)

\(\Leftrightarrow\left(2x+1-3x+4\right)\left(2x+1+3x-4\right)=0\)

\(\Leftrightarrow\left(5-x\right)\left(5x-3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{3}{5}\end{matrix}\right.\)

b) Ta có: \(5x^3-3x^2+10x-6=0\)

\(\Leftrightarrow x^2\left(5x-3\right)+2\left(5x-3\right)=0\)

\(\Leftrightarrow5x-3=0\)

hay \(x=\dfrac{3}{5}\)

a) 3x² - 6x = 0

3x(x - 2) = 0

3x = 0 hoặc x - 2 = 0

*) 3x = 0

x = 0

*) x - 2 = 0

x = 2

Vậy x = 0; x = 2

b) x² + 10x + 25 = 64

x² + 2.x.5 + 5² = 64

(x + 5)² = 64

x + 5 = -8 hoặc x + 5 = 8

*) x + 5 = -8

x = -8 - 5

x = -13

*) x + 5 = 8

x = 8 - 5

x = 3

Vậy x = -13; x = 3

c) (2 - 3x)(x + 4) + 3x - 2 = 0

(2 - 3x)(x + 4) - (2 - 3x) = 0

(2 - 3x)(x + 4 - 1) = 0

(2 - 3x)(x + 3) = 0

2 - 3x = 0 hoặc x + 3 = 0

*) 2 - 3x = 0

3x = 2

*) x + 3 = 0

x = 0 - 3

x = -3

Vậy:

a: \(27x^3-54x^2+36x-8=0\)

=>\(\left(3x\right)^3-3\cdot\left(3x\right)^2\cdot2+3\cdot3x\cdot2^2-2^3=0\)

=>\(\left(3x-2\right)^3=0\)

=>3x-2=0

=>3x=2

=>\(x=\frac23\)

b: \(x^3+15x^2+75x+125=0\)

=>\(x^3+3\cdot x^2\cdot5+3\cdot x\cdot5^2+5^3=0\)

=>\(\left(x+5\right)^3=0\)

=>x+5=0

=>x=-5

c: \(x^3-18x^2+108x-216=0\)

=>\(x^3-3\cdot x^2\cdot6+3\cdot x\cdot6^2-6^3=0\)

=>\(\left(x-6\right)^3=0\)

=>x-6=0

=>x=6

d: \(\left(x-1\right)^3-x\left(x^2+3x\right)=2\)

=>\(x^3-3x^2+3x-1-x^3-3x^2=2\)

=>\(-6x^2+3x-3=0\)

=>\(2x^2-x+1=0\)

\(\Rightarrow x^2-\frac12x+\frac12=0\)

=>\(x^2-\frac12x+\frac{1}{16}+\frac{7}{16}=0\)

=>\(\left(x-\frac14\right)^2+\frac{7}{16}=0\) (vô lý)

=>x∈∅

e: \(\left(x+1\right)^3+\left(x-2\right)^3-2x^2\left(x-1,5\right)=3\)

=>\(x^3+3x^2+3x+1+x^3-6x^2+12x-8-2x^3+3x^2=3\)

=>15x-7=3

=>15x=10

=>\(x=\frac{10}{15}=\frac23\)

a) \(x^2-64=0\)

\(\Leftrightarrow\left(x-8\right)\left(x+8\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)

b) \(4x^2-4x+1=0\)

\(\Leftrightarrow\left(2x-1\right)^2=0\Leftrightarrow2x-1=0\)

\(\Leftrightarrow x=\dfrac{1}{2}\)

c) \(9-6x+x^2=0\)

\(\Leftrightarrow\left(x-3\right)^2=0\)

\(\Leftrightarrow x-3=0\Leftrightarrow x=3\)

a: Ta có: \(x^2-64=0\)

\(\Leftrightarrow\left(x-8\right)\left(x+8\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)

b: Ta có: \(4x^2-4x+1=0\)

\(\Leftrightarrow\left(2x-1\right)^2=0\)

hay \(x=\dfrac{1}{2}\)

c: ta có: \(x^2-6x+9=0\)

\(\Leftrightarrow\left(x-3\right)^2=0\)

hay x=3

a: ta có: \(x^2+3x-\left(2x+6\right)=0\)

\(\Leftrightarrow\left(x+3\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=2\end{matrix}\right.\)

b: Ta có: \(5x+20-x^2-4x=0\)

\(\Leftrightarrow\left(x+4\right)\left(5-x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-4\\x=5\end{matrix}\right.\)

Câu 2: 

a: \(\Leftrightarrow3x^2+2x-1=0\)

\(\Leftrightarrow\left(x+1\right)\left(3x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=\dfrac{1}{3}\end{matrix}\right.\)

b: \(\Leftrightarrow x^3-4x-x^3-8=4\)

hay x=-3

bạn ơi có câu c không bạn